GROWTH AND CHARACTERIZATION OF ALAS/GAINAS MULTIPLE-QUANTUM WELLS

We have investigated several AlAs/GaxIn1-xAs multiple quantum wells (MQWs) grown on {001}GaAs substrates, consisting of 10 QWs of different thicknesses and In content varying from 1 - x = 0.08 to 1 - x = 0.15, separated by approximately 12 nm thick AlAs barriers. Samples have been grown by MBE using different substrate temperatures for the growth of AlAs barriers and GaInAs wells. Detailed double-crystal X-ray analysis has been done in all the samples, including dynamical calculations. High quality spectra and good agreement with simulated rocking curves allowed us to determine the structural parameters of each sample, both In content (strain status) and thicknesses of barriers and wells. We have measured the energies of the optical transitions associated to E0: first and second order electron-heavy hole, e-light hole and e-spin orbit transitions. Both type I and type II band alignments are observed and discussed in comparison to results of k . p calculations.